Method of improving front end octane rating and increasing &#34;lpg&#34; production



g- 3, 1965 P. EVANS 3,198,728

METHOD OF IMPROVING FRONT END OCTANE RATING AND INCREASING "LPG" PRODUCTION Filed June 20, 1962 3 Sheets-Sheet 1 4 C55 U] 3: 3; 2 5 I I z o O e IO l2 97 99 I01 I03 I05 c REFORMATE-O.N.(R+3ccTEL) FIGURE l A FEED- I80 T0 380F Ml D-CONTINENT NAPHTHA INVENTOR PRESSURE-500 PSIG LOUIS P. EVANS VAPOR INLET TEMPERATURE AND LIQUID HOURLY BY SPACE VELOCITY CORRELATED TO PRODUCE 6 REFORMATE 0F INDICATED OCTANE RATING.

Aug. 3, 1965 P. EVANS 3,198,728

METHOD OF IMPROVING FRONT END OCTANE RATING AND INCREASING "LPG" PRODUCTION Filed June 20, 1962 3 Sheets-Sheet 2 FEED-I80" TO 380F MID-CONTINENT NAPHTHA PRESSURE- 500 PSIG VAPOR INLET TEMPERATURE AND LIQUID HOURLY SPACE VELOCITY CORRELATED TO PRODUCE 0 REFORMATE OF INDICATED OCTANE RATING.

m 8 g 3 5 6 DRY GAS E 4 1 97 99 IOI I03 I05 (1 REFORMATE-O.N.(R+ 3ccTEL) FIGURE I B INVENTOR. LOUIS F. EVANS Aug. 3, 1965 L. P. EVANS METHOD OF IMPROVING FRONT END OGTANE RATING AND INCREASING "LPG" PRODUCTION 3 Sheets-Sheet 3 Filed June 20, 1962 INVENTOR LOUIS P. EVANS United States Patent Filed June 20, 1962, Ser. No. 203,814 9 Claims. (Cl. 20865) The present invention relates to reforming, and more particularly, to reforming naphtha in the presence of platinum-group metal reforming catalyst.

Recently it has been recognized that gasoline produced solely through reforming of naphtha in the presence of particle-form solid platinum group reforming catalyst generally are characterized by excessive road-octane depreciation because of the low octane rating of the reformate front end. That is to say, the C to 220 F. TBP (True Boiling Point) fraction of the reformate has an octane rating lower than the octane rating of the C to 380 F. gasoline. Thus, the C to 220 F. TBP fraction of a C to 380 F. platinum reformate had an octane rating (Research +3 cc. TEL) of 91 whereas the C to 380 F. total reformate had an octane rating (Research +3 cc. TEL) of 100.

Various modifications of the generally practiced meth- 0d of reforming naphtha to raise the octane rating thereof have been proposed to overcome this disadvantage of platinum reforming. For example, it has been proposed to fractionate the straight run naphtha into a light fraction (E.B.P. 220 to [250 F.) and a heavy fraction and to reform the light fraction at more severe reforming conditions than those at which the heavy fraction is reformed. The two reformates are then blended to provide a finished product having the required or target octane. It has also been suggested that the straight run naphtha be fractionated to provide a light fraction having an E.B.P. of 160 F. and comprising C and heavier hydrocarbons, an intermediate fraction comprising hydrocarbons boiling in the range of about 160 to about 320 F., and a heavy fraction comprising hydrocarbons boiling in the range of about 320 to about 380 F. The whole of the intermediate fraction and a portion of the heavy fraction are reformed to obtain a C and heavier reformate having an octane rating higher than the target octane rating. The C and heavier refonnates are mixed 3,198,728 Patented Aug. 3, 1965 balance of the heavy fraction to provide a blend having the aforesaid target octane rating. It has also been suggested to fractionate straight run naphtha into a light fraction, C to 250 F., and a heavy fraction, 250 to 380 F. The light fraction is reformed in the presence of platinum at a pressure of 400 p.s.i.g. or less while the heavy fraction is reformed at a pressure of 500 p.s.i.g. or more. The reformates are blended to provide a blend having the target octane rating. These and other manipulations of the basic method of reforming naphtha in the presence of platinum-group metal reforming catalyst have been proposed to overcome the disadvantage of the lower octane rating of the C to 220 F. fraction of platinum reformate and to do so in a manner to provide an improved yield of C and heavier reformate at the target octane rating. However, since all ,of the methods of raising the octane rating to at least (Research +3 cc.) require concentration of the aromatic hydrocarbons by conversion of the paraffins to hydrocarbons having less than five carbon atoms the yields of salable product has suffered. The method of the present invention, 'in contrast, provides for raising the octane rating of the C to 220 F. (TBP) fraction of reformate about four octane numbers relative to the octane rating of the C to 220 F. (T BP) fraction of conventionally produced C to 380 F. platinum reformate when the C to 380 F. platinum reformate when the C to 380 F. platinum reformate has an octane rating (Research +3 cc. TEL) of 99 while the volume of salable product, as L.P.G., is increased with little change in the volume of C and lighter hydrocarbons. Thus, when producing C and heavier reformate having octane ratings (Research +3 cc. TEL) in the range of 97 to 103 the yield of 0 reformate is about 7.2 to about 12.2 percent by volume less than the volume of C reformate produced in conventional reforming in the presence of platinum-group metal reforming catalyst. On theother hand, the volume of C s is 11 to 14 percent greater than the volume of C s produced in conventional reforming in the presence of platinum-group metal reforming catalyst while the quantity of C s is about 3 to about 7 percent by weight less than the Weight of the C s produced when reforming by the method of the present invention. However, the total dry gas produced when reforming in accordance with the present method is only about 2 to about 5 percent by weight greater. The pertinent data as set forth with the unreformed light fraction and the unreformed 111 Table I.

Table 1 Catalyst Pt NiWS NiWS Pt NiWS N iWS Pt NiWS N iWS Pt NiWS NiWS Fill Ratio 0.2/0.2/l.0 0.53/0.53/1.62 .2/.2/1.0 153/.53/152 .2/.2/1.0 .53/.53/l.62 .2/.2/l.0 .53/.53/1.62

O.N (R-I-3 cc.) of

05+ reformate 97 97 97 100 100 100 103 103 103 105 105 105 0 reformate, vol.

percent of charge 91. 2 92.0 +0. 8 89. 2 90. 4 +1. 2 85.0 86. 9 +1.9 81.0 82. 6 +1.6 C reformate, vol.

percent of charge 87. 4 80. 3 7. 1 83. 7 73. 7 10. 0 77.8 66. 2 --11. 6 r 73.0 60. 8 12. 2 0 reformate, vol.

percent of charge 82. 3 70. 9 l1. 4 77. 3 62. 8 14. 5 70. 4 54. 2 l6. 2 65. 3 48. 6 16. 7 Total 055, vol. percent of charge 5. 1 9. 4 +4. 3 6. 4 10. 9 +4. 5 7. 4 12. 0 +4. 6 7. 7 12. 2 +4. 5 Total C4s, vol. pere e cent of charge 3.8 11. 7 +7. 9 5. 5 16. 7 +11. 2 7. 2 20. 7 +13. 5 8.0 21. 8 +13. 8 03 wt. percent of charge 3. 0 6. 2 +3. 2 4. 2 8. 6 +4. 4 5. 5 11. 4 +5. 9 6. 3 13. 4 +7. 1 Dry gas, Wt. percent of charge 6. 7 9. 0 +2. 3 9. 2 12. 4 +3. 2 12. 3 16. 5 +4. 2 14. 8 19. 9 +5. 1

The differences are graphically presented in FIGURES 1A and 1B of the drawings.

Inspection of FIGURES 1A and IE will establish that the production of C s and C s for L.P.G. (Liquid Petroleum Gas) is from about percent to about 21 percent greater when reforming the 180 to 380 F. fraction of Mid-Continent naphtha by the present method than the production of C s and C s when reforming the 180 to 380 F. fraction of Mid-Continent naphtha by the conventional method.

As used hereinbefore and hereafter conventional platinum reforming is used to designate reforming of naphtha in the presence of particle-form solid platinumgroup metal reforming catalyst, e.g., comprising 0.35 to about 1.0 percent by Weight of platinum and about 0.35 to about 1.0 percent of chlorine on alumina support, at a pressure in the range of 500 to 1200 p.s.i.g., at a vapor inlet temperature in the range of 900 to l,000 F., at an overall liquid hourly space velocity of about 0.5 to about 2.0 in the presence of hydrogen in the mol ratio of about 6 to about 10 mols of hydrogen per mol of naphtha feed and correlating the activity of the catalyst, the liquid hourly space velocity, and the vapor inlet temperature of the reactors to produce C reformate having the desired or target octane rating (Research +3 cc. TEL).

In general the present method of producing gasoline having a front end octane, i.e., the octane rating of the C to 220 F. (TBP) fraction, about 3 to 5 octane numbers higher than the front end octane of conventionally reformed naphtha comprises contacting a 180 to 380 F. boiling range naphtha with platinum-group metal reforming catalyst at a pressure of at least 500 p.s.i.g., at a liquid hourly space velocity and reactor(s) vapor inlet temperature(s) dependent upon the dehydrogenating activity of the platinum-group metal reforming catalyst to convert at least a preponderant portion of the naphthenes to aromatics and in a subsequent treatment contacting previously reformed naphtha with catalyst at a pressure of at least about 500 p.s.i.g., at a liquid hourly space velocity and reactor vapor inlet temperature dependent upon the dealkylation and hydrocracking activity of the sulfide catalyst to produce C reformate having the target octane rating and the aforesaid increased yield of C s and C s. Suitable catalysts for the aforesaid subsequent treatment include catalyst comprising at least one sulfide of nickel and a sulfide of tungsten on a support comprising about 5 to about percent by Weight of alumina, about 85 to about 95 percent by weight of silica and the balance substantially water, e.g., comprising about 4 percent by Weight of nickel, about 11 percent by Weight of tungsten, and about 5 percent by Weight of sulfur on a refractory oxide support comprising about 9.7 percent by weight of alumina, about 89.4 percent by weight of silica, about 0.2 percent by weight of chromia, and about 0.7 percent by Weight of water. Other illustrative catalyst compositions suitable for the aforesaid subsequent treatment are set forth in the following tabulation:

Illustrative of the reaction conditions are the following:

Table I DEHYDRO GENATION STAGE Catalyst:

0.35 percent by weight of platinum and 0.4 percent by weight of chlorine on A1203 support Reaction Conditions l Gcncrnl Preferred Pressure, p.s.ig 500 to 1, 200 500 to 750 Vapor Inlet Temp. F 800 to 1,050 850 to 950 Liquid Hourly Space Velocity, V /lm/V 0. 5 to 3.0 1. 0 to 2.0 Hydrogen-to-naphthn. mol ratio 4 to 15 6 to 12 V =volurne 0i naphtha; V =v0lumc of catalyst.

DEALKYLATION STAGE Thus, for example, the 180 to 380 F. (TBP) fraction of Mid-Continent naphtha, commonly designated dehexanizcd naphtha, was contacted with platinum group metal reforming catalyst comprising about 0.6 percent by weight of platinum and about 0.7 percent by weight of chlorine on alumina support at a pressure of 500 p.s.i.g., a hydrogen-to-naphtha mol ratio of 10 to 1, and an overall liquid hourly space velocity of about 1.5 at vapor inlet temperature to convert about 94 to about 98 percent by volume of the naphthenes to aromatics. The elfluent of the dehydrogenation stage was then contacted with the aforedescribed nickel-tungsten-sulfur catalyst at a pressure of 500 p.s.i.g., a hydrogen-to-naphtha mol ratio of 10 to 1, and an overall liquid hourly space velocity of about 1.0 at vapor inlet temperature('s) to produce C reform-ate of the target octane rating.

It is to be observed that when dehexanized, i.e., 180 to 380 F., Mid-Continent naptha is dchydrogenated only in a dehydrogenation stage having two dehydrogenation zones under the conditions set forth hereinafter in Table.

III about 94 percent by volume of the naphthenes in the feed are converted:

Table III Catalyst:

0.35 percent by weight 01 platinum and 0.4 percent by weight of chlorine on alumina support.

Pressure, p.s.Lg 500 500 Reaction Zone R Vapor Inlet Temp. F 980 Liquid Hourly Space Velo Vn o 15 Overall Liquid Hourly Space Velocity, Vn/hn/Vc Feed, 180 Change in Hydrocarbon Class, percent vol. 380 F., Raw Product M-O Rclormate Composi- Naphtha tion C2 to C Paratfins 1. 0 9. 5 +8. 5 C5 to C Parafl'ms 46.0 39. 0 7.0 C; to C5 Olclins 0. I +0.1 06+ Olefins 1.3 +1.3 C to C1; Aromatics 7. 5 47. 4 +39. 9 Naphthenes 42. 5 2. 7 39. 8 Others 3.0 0.0 3. 0 Tota 100. 0 100.0 Octane Rating:

Research (Clear) .8. 0 Research (R+3 cc. TEL) 72. 3 97. 1 +24. 8

When the same dehexanized Mid-Continent naphtha, i.e., the 180 to 380 F. fraction of Mid-Continent naphtha is reformed under the following conditions (Table IV) conversion of the naphthenes is about to 98 percent by volume.

Table IV Feed:

180 to 380 F. fraction of Mid-Continent naphtha Catalyst:

0.35 percent by weight of platinum and 0.4 percent by weight of chlorine on alumina support.

Run N0 -158-4 20-158-6 Reactor No R1 R2 R3 R1 R2 R3 Barrels of Catalyst Charge/10,000 b./d 27. 8 139 Liquid Hourly Space VelocityNn /hr./V 15 3 Overall Liquid Hourly Space Velocity, 2 5

Total B blsfofbatalyst Charged/10,000 b./d- 100 s Vapor Inlet Temperature 960 960 1, 049

Octane Rating of 0 Reformate (Research +3 00. TEL) 100. 2

Composition of Raw Reformate, Percent Volume:

C5 and Lighter Paraifins 7. 6 5. 4 C5 and Lighter Olefins 1. 4 2. 2 C0 and Heavier Paratfins 31. 5 -14. 5 23. 6 22. 4

C0 and Heavier Olefins- 2. 5 1. 6

Cu and Heavier Aromat 54.8 +47.3 65.9 +58.4

Naphthenes 2.2 40.3 0.8 41.7

Others 0.0 0.5

Total 100. 0 100. 0

Total 05 and Lighter-.. 9.502 2 9 8 Total 0 Naphthenes Converted, Per- 2 =95 j '-=98 cent by Volume.

It is to be observed that dehydrogenating the charge [Operating Cmldititmsl naphtha in the presence of the minimum quantity of platinum-group metal reforming catalyst required to con- Ream R1 R2 R3 vert at least 90 percent of the naphthenes in the feed to aromatics 1s concomitant with a saving of about $350,000 zil g gf F 850 1532 93? 85? $5 52 850 go 5,393 in t e C s f the ataly fi r a t g g 00 Pressuie,'ii.s.i. fff: I: 500 to 750 5001:0750 500120750 1 I Hz to Naphtha mol Ratio 6 to 12 6 to 12 6 to 12 barren or naph.ha daily. In addition the sale or L.P.G. 3.) Overall LHSVVJMJVN Loto and gasoline product nets a return substantially equal to that obtamed reformmg naPhtha of substantially -Vn/hr./v Volume of hydrocarbon per hour per volume of catalyst in the same composition to substantially the same octane the reactor. rating employing platinum-group metal reforming catalyst y ggg gg of hydrocarbm Per per volume of catalyst as the sole reforming catalyst. 40 LHSVLiquid Hourly Space Velocity.

A g the f mventlon prcfvldes for Illustrative of suitable naphtha fraction for treatment tactmgnap tha EP P not more t mflocuous in the method of the present invention are naphthas hav-- centrations of sul ur, n trogen and arsenic in a dehydroing the characteristics set forth in Table VI. genation stage comprising at least two adiabatic reactors with particle-form solid platinum-group metal reforming Table VI catalyst at an overall liquid hourly space velocity in the dehydrogenation stage in the range of about 1.0 to about 80 to 380 F. 200 to 400" F. 3.0, reheating the total efiluent of the dehydrogenation ;%f,,3; figg ggg stage and contacting the reheated dehydrogenation stage Naphtha Naphtha total effluent with non-noble metal catalyst as defined hereinbefore at an overall liquid hourly space velocity of Distillation, ASTM F about 1.0 to about 3.0. 7 $575 The naphtha feed has a composition in the ranges set Volume 222 240 forth in Table V. The platinum-group reforming catalyst 553 gig preferably has a composition in the range set forth in 383 390 Table V. The non-noble metal catalyst preferably has a '2 '2 composition set forth in Table V. The reforming con- 2 (litions preferably are those set forth in Table V. I 2

Total Parafiins, Vol. Percent 47. 0 01. 2

Table V Total Aromatics, Vol. Percent 7. 5 11. 9

Total Naphthenes, Vol. Percent 425 26. 9

[Feed] Total Others, v01. Percent .0 0.0

Boiling Range, F 180-380 250-400 0 Octane Ratings Research, Clear 48.0 33. 2

g g g g g g g3 g 5 60 01055 015 TEL 12% 22% o ercen ap enes o o 00 Vol. Percent Aromatics 7 to 12 9 to 15 G5 Motor +3 TEL 0 5 Vol. Percent Others 0 to 2 0 to 2 genating catalyst having capabilities of hydrodesulfuriza tion, hydrodenitrogenation, and hydrodearsensation, if necessary) is contacted With particle-form solid platinum-- group metal reforming catalyst in a naphthene dehydrogenation stage comprising one or more reaction zones and then is contacted with non-noble metal or sulfide cata-- lyst comprising sulfide of one or more of the metals, nickel, tungsten, and molybdenum as illustrated in the fiowsheet FIGURE 2 of the drawings. On the other hand, the naphtha is fractionated, preferably after hydrodecontamination, to provide a light fraction having an end boiling point in the range of about 250 to 280 F. and a heavy fraction having a 10 percent point not lower than the 90 percent point of the light fraction and an end boiling point in the range of about 380 to about 420 F. The light fraction is. contacted with particleform solid platinum-groupmetal reforming catalyst to produce C reformate having an octane rating (Research +3 cc. TEL) in the range of about 94 to about 105 while the heavy fraction is contacted in the presence of hydrogen with non-noble metal catalyst described hereinbefore to produce (1 reformate having an octane rating (Research +3 cc. TEL) in the range of about 95 to about 100. The platinum group metal C reformate from the light fraction in whole or in part is blended with the whole or a part of the non-noble metal (3 reformate obtained from the heavy fraction to provide CD blend having the target octane rating (Research +3 cc. TEL) in the range of about 95 to about 104.

Innocuous concentrations of sulfur, nitrogen, and arsenic as used herein are, for sulfur not more than ppm; for nitrogen not more than 1 p.p.m.; for arsenic not more than 2 p.p.b. i.e., 2/10 Preferably the naphtha charged to the reactors containing particle-form solid platinum-group metal reforming catalyst is essentially free of arsenic. As used herein essentially free of arsenic designates a concentration of arsenic in a reformer feed determined by other factors such as the temperature required to produce a C reformate having an octane rating of at least 100 (Research +3 cc. TEL), the yield of reformate, and the mechanical strength of the catalyst.

The fiowsheet FIGURE 2 illustrates alternative embodiments of the present invention. In the preferred embodiment naphtha containing not more than innocuous (as defined herein) concentrations of sulfur, nitrogen and arsenic and having an end boiling point in the range 380 F. to 420 F. is dehydrogenated in the presence of platinum-group metal reforming catalyst and hydrogen (after start up recycle gas containing hydrogen) and bydroreformed in the presence of sulfide catalyst defined hereinbefore. tion having an end boiling point in the range 250 to 280 F. is dehydrogenated in the presence of platinumgroup metal reforming catalyst while the heavy fraction having an end boiling point in the range 380 F. to 420 F. is hydroreformed in the presence of the aforesaid sulfide catalyst and hydrogen.

In the preferred embodiment as illustrated in FIGURE 2 the 180 to 380 P. fraction of naphtha containing at least percent by volume of naphthenes is drawn from a source not shown through pipe 1 by pump 2. Pump 2 discharges the feed naphtha into pipe 3 at a pressure greater than the pressure in reactor 14 by at least the pressure drop between pump 2 and reactor 14. The feed naphtha flows through pipe 3 (valve 5 open; valve 115 closed) to pipe 4 and thence to indirect heat exchanger 6 where the feed naphtha is in heat transfer relation with the effluent of reactor 26 flowing from indirect heat exchanger 8 through conduit 28. From indirect heat exchanger 6 the feed naphtha flows through pipe 7 to indirect heat exchanger 8 where the feed naphtha is in heat transfer relation with the effluent of reactor 26 flowing therefrom through conduit 27. From indirect heat exchanger 8 the feed naphtha flows through conduit 9 (valve 10 open; valves 103 and 117 closed) to coil 11 in heater or furnace 12. At a point in conduit 9 intermediate to heater 12 and to heat exchanger 8 hydrogen-con- In an alternative embodiment a light fractaining gas, specifically reformer recycle gas after startup, flowing from compressor 34 through conduit 35 at a pressure at least equal to that in conduit 9 is admixed with the feed naphtha or charge naphtha to provide a charge mixture having a hydrogen-to-naphtha mol ratio in the range set forth hereinbefore.

In furnace 12 the charge mixture is heated to a reforming temperature to provide at the vapor inlet of reactor 14 of the dehydrogenation stage a vapor inlet reforming temperature in the range set forth hereinbefore. The heated charge mixture flows from furnace 12 through conduit 13 to reactor 14. The heated charge mixture at reforming temperature flows downwardly through reactor 14 in contact with particle-form solid paltinumgroup metal reforming catalyst to the outlet of reactor 14. The efiluent of reactor 14 flows therefrom through conduit 15 to coil 16 in furnace or heater 17. In heater or furnace 17 the first efiluent is reheated to provide at the vapor inlet of reactor 19 a reforming temperature the same as, or higher than, or lower than, the vapor inlet temperature of reactor 14. The reheated first efiluent flows from furnace 17 through conduit 18 to reactor 19. The reheated first efiluent flows downwardly through reactor 19 in contact with particle-form solid platinumgroup metal reforming catalyst to the outlet thereof. The efiluent of reactor 19, i.e., the second efiluent, having a concentration of naphthenes not greater than about 2 percent by volume of the naphthenes present in the feed naphtha to provide a C reformate having an octane rating (Research +3 cc. TEL) of 104 and not greater than about 10 percent by volume of the naphthenes in the feed naphtha to provide a C reformate having an octane rating (Research +3 cc. TEL) of 95 flows therefrom through conduits 20 and 22 to coil 23 in furnace or heater 24. (Valve 21 open; valves 109, 117 and 119 closed.) In heater 24 the second effluent is reheated to provide at the vapor inlet of reactor 26 a sulfide-reforming temperature in the range of about 850 to about 1,000 F. From heater 24 the reheated second effiuent flows through conduit 25 to reactor 26. In reactor 26 the reheated second efliuent flows downwardly in contact with the particle-form solid non-noble sulfide catalyst to the outlet thereof. The final effluent flows from reactor 26 through conduit 27 to indirect heat exchanger 8, conduit 28, indirect heat exchanger 6 and conduit 29 to cooler 120 (valve 122 open, valve 123 closed.) In cooler 120 the final efiluent is cooled to a temperature at which at the existing pressure C and heavier hydrocarbons are condensed. The cooled final efiluent flows from cooler 120 through conduit 121 to liquid-gas separator 30. In separator 30 the uncondensed final effluent, designated reformer gas, comprising hydrogen, methane and ethane separates from liquidC and heavier hydrocarbons. The reformer gas flows from separator 30 through conduit 31 to compressor 34. A portion of the reformer gas about equal to the gas made in reactors 14, 19 and 26, i.e., the make-gas is diverted through conduit 33 under control of valve 32 to the refinery fuel main, or to recovery or to conversion of the methane and ethane to salable products. The balance of the reformer gas, designated recycle gas, flows through conduit 31 to the suction side of compressor 34. Compressor 34 discharges the recycle gas into conduit 35 at a pressure at least equal to that in conduit 9. The compressed recycle gas flows through conduit 35 to conduit 9 to mix with the feed naphtha to form the charge mixture as previously described.

The condensed final efiluent comprising C and heavier hydrocarbons and designated raw reformate flows through pipe 36 to the suction side of pump 37. Pump 37 discharges the raw reformate into pipe 38. The raw reformate flows through pipe 38 to indirect heat ex changer 39 where the raw reformate is in heat transfer relation with the bottoms, i.e., C reformate, of stabilizer 43 flowing from indirect heat exchanger 41 through pipe 47. From indirect heat exchanger 39 the raw reformate flows through pipe 40 to indirect heat exchanger 41 where the raw reformate is in heat transfer relation with the C reformate flowing from stabilizer 43 through pipe 46. From indirect heat exchanger 41 the raw reformate flows through pipe 42 to stabilizer 43.

In stabilizer 43 a temperature is maintained at which C and lighter hydrocarbons are volatile. Accordingly, an overhead comprising ethane and lighter hydrocarbons is taken through pipe 44 with suitable reflux (not shown), a side stream comprising C and C hydrocarbons is taken through pipe 45, and a bottoms comprising C and heavier hydrocarbons flows from stabilizer 43 through pipe 46, indirect heat exchanger 41, pipe 47, indirect heat exchanger 39 and pipe 48 to storage, the addition of additives, blending and distribution.

Those skilled in the art will recognize that the single stabilizer of FIGURE 2 there can be employed a deethanizer, a de-propanizer, a de-butanizer and a de-pentanizer.

For the dehydrogenation of light naphtha, having an end boiling point in the range of 250 to 280 F., in the presence of hydrogen and particle-form solid platinumgroup metal reforming catalyst and reforming of heavy naphtha, having an end boiling point in the range 380 to 420 F. in the presence of sulfide reforming catalyst the flow of liquids and gases is also illustrated in FIGURE 2. Thus, a light naphtha having an end boiling point in the range of 250 to 280 F. and containing not more than innocuous concentrations of sulfur, nitrogen and arsenic flows from a source not shown through pipe 101 to the suction side of pump 102. Pump 102 discharges the light fraction into pipe 103 at a pressure greater than the pressure in reactor 14. The light fraction flows through pipe 103 to indirect heat exchanger 104 where the light fraction is in heat transfer relation with the efiluent of reactor 19 designated platinum reaction prod ucts, flowing from reactor 19 through conduit 20 (valve 21 closed; valve 109 open), indirect heat exchanger 106 and conduit 110 to indirect heat exchanger 104. From heat exchanger 104 the light fraction flows through pipe 105 to indirect heat exchanger 106 where the light fraction is in heat transfer relation with the platinum reaction products flowing from reactor 19 through conduit 20 (valve 109 open; valve 21 closed). From indirect heat exchanger 106 the light fraction flows through pipe 107 to conduit 9 (valve 108 open; valve 10 closed). In conduit 9 the light fraction is mixed wtih hydrogen-containing recycle gas (after start-up) flowing from compressor 34 through conduit 35 to form a light charge mixture. In furnace 12 the light charge mixture is heated to provide a vapor inlet reforming temperature at the vapor inlet of reactor 14 in the range set forth hereinbefore. The light charge mixture flows downwardly through reactor 14 in contact with particle-form solid platinumgroup metal reforming catalyst. The efliuent of reactor 14, designated first light efiiuent, flows from reactor 14 through conduit 15 to coil 16 in heater 17.

In heater 17 the first light efliuent is reheated to a temperature to provide at the vapor inlet of reactor 19 a reforming temperature the same as, higher than, or lower than the vapor inlet temperature at reactor 14. The reheated first light eifiuent flows from furnace '17 through conduit 18 to reactor 19. In reactor 19 the reheated first light effiuent flows downwardly in contact with particleform solid platinum-group metal reforming catalyst. The effluent from reactor 19, designated final light efliuent, flows from reactor 19 through conduit 20 (valve 21 closed; valve 109 open) to indirect heat exchanger 106, conduit 110, indirect heat exchanger 104 and conduit 111 to conduit 29 (valve 122 closed). The final light efliuent flows through conduit 29 to cooler 120. In cooler 120 the final light effluent is cooled to a temperature at which C and heavier hydrocarbons are condensed at the existing pressure. The cooled final light effluent flows from cooler 120 through conduit 121 to liquid gas separator 30.

In separator 30 the uncondensed final efiluent comprising hydrogen, methane and ethane and designated reformer gas separates from the condensed final effluent designated raw light reformate. The reformer gas flows from separator 30 through conduit 31 to compressor 34 in amount sufficient to supply the requirements for hydrogen in reforming the light fraction in reactors 14 and 19 and the requirements for hydrogen in reactor 26. The balance of the reformer gas is diverted through conduit 33 under control of valve 32 to means for recovery of hydrogen and/ or conversion of methane and ethane to other products, e.g., methane to acetylene and ethane to ethylene.

The raw light reformate flows from separator 30 through pipe 36 to the suction side of pump 37. Pump 37 discharges the raw light reformate into pipe 38. In pipe 33 the raw light reformate is mixed with the raw heavy reformate flowing from pump 130 through pipe 131. (Since from this point in the illustrative flow the flow of light raw reformate, admixed with heavy raw reformate, designated mixed raw reformate, is the same, the description of the illustrative flow of the heavy fraction, i.e., the fraction having an EBP in the range of about 380 to about 420 F. and the reaction products obtained therefrom will be described.)

The heavy fraction, i.e., the fraction having an end boiling point (EBP) in the range of about 380 to about 420 F. and an initial boiling point (IBP) not lower than about the percent point of the light fraction of naphtha flows from a source not shown through pipe 112 to the suction side of pump 113. Pump 113 discharges the heavy fraction into pipe 114 (valve 115 open; valve 5 closed) at a pressure in excess of that in reactor 26. The heavy fraction flows through pipe 114 to pipe 4 and thence to indirect heat exchanger 6. In indirectheat exchanger 6 the heavy fraction is in heat transfer relation with heavy efliuent flowing from indirect heat exchanger 8 through conduit 28. From indirect heat exchanger 6 the heavy fraction flows through pipe 7 to indirect heat exchanger 0 where the heavy fraction is in heat transfer relation with the heavy effluent flowing from reactor 26 through conduit 27. From indirect heat exchanger 8 the heavy fraction flows through conduit 9 (valve 10 closed; valve 117 open) to conduit 116 and thence to conduit 22 (valve 21 closed). At a point in conduit 116 intermediate to valve 117 and conduit 22, hydrogen-containing gas (reformer recycle gas after start-up) flowing from compressor 34 through conduits 35 and 118 under control of valve 119 is admixed with the heavy fraction to provide a heavy charge mixture containing hydrogen and naphtha in the range of mol ratios set forth hereinbefore, i.e., 6 to 12. The heavy charge mixture flows through conduit 116 to conduit 22 and thence to coil 23 in furnace or heater 24. In heater 24 the heavy charge mixture is heated to a temperature to provide at the vapor inlet of reactor 26 a reforming temperature in the range of about 850 F. to about 1,000 F.

The heavy charge mixture flows downwardly through reactor 26 in contact with sulfide catalyst described hereinbefore. The efliuent of reactor 26, designated heavy efiiuent as stated hereinbefore, flows from reactor 26 through conduit 27, indirect heat exchanger 8, conduit 28 and indirect heat exchanger 6, and conduits 29 and 124 (valve 122 closed; valve 123 open) to cooler 125.

In cooler 125 the heavy efiiuent is cooled to a temperature at which C and heavier hydrocarbons are condensed at the existing pressure. The cooled heavy effluent flows from cooler 125 through conduit 126 to gas-liquid separator 127. a

In'separator 127 the uncondensed heavy efiiuent comprising hydrogen, methane and ethane separates from the condensed heavy effluent comprising C and heavier hydrocarbons. The uncondensed heavy effluent, designated excess gas flows from separator 127 through conduit 128 to means for the recovery of hydrogen, to the refinery fuel main, to means for converting methane to acetylene and ethane to ethylene for example, or to other uses for which gas of this composition is suitable.

The condensed heavy eiliuent, designated raw heavy reformate, comprising C and heavier hydrocarbons flows from separator 127 through pipe 129 to the suction side of pump 130. Pump 130 discharges the raw heavy reformate into pipe 131 through which the heavy reformate flows to pipe 38 for admixture with raw light reformate. The mixture of raw light reformate and raw heavy reformate comprising C and heavier hydrocarbons designated mixed raw reformate, flows through pipe 38 to indirect heat exchanger 39 where the mixed raw reformate is in heat transfer relation with the bottoms, (1 reformate, flowing from indirect heat exchanger 41 through pipe 47. From indirect heat exchanger 39 the raw reformate flows through pipe 40 to indirect heat exchanger 41 where the mixed raw reformate is in heat transfer relation with the bottoms of stabilizer 43 flowing therefrom through pipe 46. From indirect heat exchanger 41 the raw reformate flows through pipe 42 to stabilizer 43. (Those skilled in the art are cognizant of the fact that the stabilization of the raw reformate can be carried out in one or in a plurality of fractionating columns.)

In stabilizer 43 ethane and lighter hydrocarbons are taken overhead (with suitable reflux not shown) through conduit 44 to the refinery fuel main, recovery of the hydrocarbons or conversion of the hydrocarbons into salable products. A C and 0.; fraction is taken (with suitable reflux not shown) as a side stream through pipe 45 to storage as L.P.G. product, recovery as separate hydrocarbons, to conversion to other hydrocarbons, for example, propane to propylene, butane to butylene, and the like.

The bottoms product comprising C and heavier hydrocarbons flows from stabilizer 43 through pipe as, indirect heat exchanger 41, pipe 47, indirect heat exchanger 39 and pipe 48 to storage, blending, addition of additives, and/ or distribution.

Those skilled in the art will recognize that when the treatment in the second stage is in the presence of sulfide catalyst as defined herein not only is there a capital saving of about $350,000 for the reforming of 10,000 barrels of naphtha per day but in addition there is the increased production of L.=P.G. which in some refineries provides increased revenue of about $1,350 per day per 10,000 barrels of naphtha reformed.

As used herein overall liquid hourly space velocity is the ratio of the volume of hydrocarbon mixture contacted per hour with the total catalyst in any stage or the total catalyst in both stages as is evident from the context.

I claim:

1. A method of reforming naptha containing napthenes and parafhns which comprises in a first and dehydrogenation stage contacting dehexanized charge naphtha comprising naphthenes and paraffins having an IBP in the range of about 180 F. to about 200 F. and an EBP in the range of 380 F. to 420 F. in the presence of hydrogen with platinum-group metal reforming catalyst at naphthene-dehydrogenating conditions of vapor inlet temperature in the range of about 800 to about 1,050 F., of pressure in the range of about 500 to about 1,200 p.s.i.g., and of liquid hourly space velocity of at least about 0.5 obtaining dehydrogenation stage reaction products comprising hydrogen and C and heavier hydrocarbons, the C and heavier portion of the aforesaid C and heavier hydrocarbons containing not more than about two to about ten percent of the naphthenes of the aforesaid dchexanized charge naptha, in a second stage contacting substantially all of the aforesaid dehydrogenation stage reaction products with non-noble metal sulfide catalyst at a pressure in the range of about 500 to about 1,500 p.s.i.g., at a vapor inlet temperature in the range of about 800 to about 1,100 E, and at a liquid hourly space velocity of at least 0.5, and recovering (1) reformer gas comprising hydrogen, (2) liquid petroleum gas comprising (3 and C hydrocarbons and (3) C and heavier hydrocarbons having an octane rating at least 15 octane units higher than the octane rating (Research-H cc. TEL) of said dehexanized charge naptha of which C and heavier hydrocarbons the C to 220 F. (TBP) fraction has an octane rating about four octane numbers higher than the octane rating (Research-F3 cc. TEL) of the C to 220 F. (TBP) fraction of conventionally produced C to 380 F. platinum reformate.

2. The method set :forth in claim 1 wherein the nonnoble metal sulfide catalyst is nickel-tungsten sulfide catalyst.

3. A method of reforming naphtha containing naphthenes and par affins which comprises in a first and dehydrogenation stage contacting first naphtha having an end boiling point in the range of about 250 to about 280 F. in the presence of hydrogen with platinum-group metal reforming catalyst at naphthene-dehydrogenating conditions of vapor inlet temperature in the range of about 800 to about 1,050 F., of pressure in the range of about 500 to about 1,200 p.s.i.g., and the liquid hourly space velocity of at least about 0.5, obtaining dehydrogenation stage reaction products comprising hydrogen and C and heavier hydrocarbons, the C and heavier portion of the aforesaid C and heavier hydrocarbons containing not more than about two to about ten percent of the naphthenes of the aforesaid first naphtha, separating said dehydrogenation stage reaction products into (1) reformer gas comprising hydrogen and (2) light reformate comprising C and heavier hydrocarbons, in a second stage contacting second naphtha comprising naphthenes and parafins having an EBP not lower than about the percent point of said first naphtha and an EBP in the range of about 380 to about 420 F. with non-noble metal sulfide catalyst in the presence of hydrogen at a pressure in the range of about 500 to about 1,500 p.s.i.g., at a temperature in the range of about 800 to about 1,100 F., and at a liquid hourly space velocity of at least 0.5, obtaining second stage reaction products comprising hydrogen, and C and heavier hydrocarbons, separating said second stage reaction products into (1) reformate and said heavy reformate to obtain mixed reformate comprising C and heavier hydrocarbons, mixing said light reformate and said heavy reformate to obtain mixed reformate, separating said mixed reformate into 1) liquid petroleum gas comprising C and C hydrocarbons and (2) stabilized reformate comprising C and heavier hydrocarbons, of said stabilized reformate the C to 220 F. (TBP) fraction having an octane rating about four octane numbers higher than the octane rating (Research-H cc. TEL) of the C to 220 F. (TBP) fraction of conventionally produced C to 380 F. platinum reformate.

4. The method set forth in claim 3 wherein the nonnoble metal sulfide catalyst is nickel-tungsten sulfide catalyst.

5. The method set forth in claim 3 wherein the liquid hourly space velocity in the dehydrogenation stage is about 2.0 to about 4.0.

6. The method set forth in claim 1 wherein the dehydrogenation stage comprises at least two reaction zones, and wherein the liquid hourly space velocity in the first of said reaction zones in which the dehydrogenation of naphthenes occurs is in the range of about 10 to about 20 and the overall liquid hourly space velocity for the hydrogenation stage is in the range of about 2.0 to about 5.0.

7. The method set forth in claim 6 wherein the liquid hourly space velocity in the second stage is in the range of about 1.0 to about 3.0.

8. The method set forth in claim 6 wherein the second stage is charged with nickel-tungsten sulfide catalyst, and

wherein the overall liquid hourly space velocity for the 13 14 dehydrogenation stage and the second stage is in the References Cited by the Examiner range of about 1.0 to about 3.0.

9. The method set forth in claim 8 wherein the de- UNITED STATES PATENTS hydrogenation stage comprises at least two reaction zones, 2,758,062 8/56 Anmdale et a1 208-65 wherein the liquid hourly space velocity in the first of 5 2,909,477 10/59 Muller 20865 said reaction zones is in the range of about 15, and 2,944,005 7/ 60 Scott wherein the overall liquid hourly space velocity for the 3,017,344 1/62 Woodle 20865 dehydrogenation stage and the second stage is in the 3,037,930 6/62 Mason 208*112 range of about 1.0 to about 3.0. ALPHONSO D. SULLIVAN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,198,728 August 3, 1965 Louis P. Evans It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 13, for "94" read 95 column 12, lines 43 and 44, for "(1) reformate and said heavy reformate to obtain mixed" read (l) reformer gas comprising hydrogen and (2) heavy lines 66 and 67, for "hydrogenation" read dehydrogenation Signed and sealed this 18th day of January 1966.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents 

1. A METHOD OF REFORMING MAPTHA CONTAINING NAPTHENES AND PARAFFINS WHICH COMPRISES IN A FIRST AND DEHYDROGENATION OF STAGE CONTACTING DEHEXANIZED CHARGE NAPTHA COMPRISING NAPTHENES AND PARAFFINS HAVING AN IBP IN THE RANGE OF ABOUT 180*F. TO ABOUT 200*F. AND AN EBP IN THE RANGE OF 380*F. TO 420*F. IN THE PRESENCE OF HYDROGEN WITH PLATINUM-GROUP METAL REFORMING CATALYST AT MAPTHENE-DEHYDROGENATING CONDITIONS OF VAPOR INLET TEMPERATURE IN THE RANGE OF ABOUT 800* TO ABOUT 1,050*F., OF PRESSURE IN THE RANGE OF ABOUT 500 TO ABOUT 1,200 P.S.I.G., AND OF LIQUID HOURLY SPACE VELOCITY OF AT LEAST ABOUT 0.5, OBTAINING DEHYDROGENATION STAGE REACTION PRODUCTS COMPRISING HYDROGEN AND C1 AND HEAVIER HYDROCARBONS, THE C5 AND HEAVIER PORTION OF THE AFORESAID C1 AND HEAVIER HYDROCARBONS CONTAINING NOT MORE THAN ABOUT TWO TO ABOUT TEN PERCENT OF THE NAPTHENES OF THE AFORESAID DEHEXANIZED CHARGE NAPTHA, IN A SECOND STAGE CONTACTING SUBSTANTIALLY ALL OF THE AFORESAID DEHYDROGENATION STAGE REACTION PRODUCTS WITH NON-NOBLE METAL SULFIDE CATALYST AT A PRESSURE IN THE RANGE OF ABOUT 500 TO ABOUT 1,500 P.S.I.G., AT A VAPOR INLET TEMPERATURE IN THE RANGE OF ABOUT 800 TO ABOUT 1,100*F., AND AT A LIQUID HOURLY SPACE VELOCITY OF AT LEAST 0.5, AND RECOVERING (1) REFORMER GAS COMPRISING HYDROGEN, (2) LIQUID PETROLEUM GAS COMPRISING C3 AND C4 HYDROCARBONS AND (3) C5 AND HEAVIER HYDROCARBONS HAVING AN OCTANE RATING AT LEAST 15 OCTANE UNITS HIGHER THAN THE OCTANE RATING (RESEARCH&3CC. TEL) OF SAID DEHEXANIZED CHARGE NAPTHA OF WHICH C5 AND HEAVIER HYDROCARBONS THE C5 TO 220*F. (TBP) FRACTIONS HAS AN OCTANE RATING ABOUT FOUR OCTANE NUMBERS HIGHER THAN THE OCTANE RATING (RESEARCH&3 CC. TEL) OF THE C5 TO 220*F. (TBP) FRACTION OF CONVENTIONALLY PRODUCED C5 TO 380*F PLATINUM REFORMATE. 